<h2>Background information</h2>
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  <accordion-group heading="Which version control system do you use?">
	I used to use Github.
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  <accordion-group heading="Which tool do you use to do test so many versions?">
	Thanks for noticing there is quite some test work.
I use junit. The junit tests are in the github repository. running some of them takes a very long time.
  </accordion-group>
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